Blood in the urine — what it means and when to act

Blood in the urine — haematuria — is one of those symptoms that should always make you pause. Most causes are treatable, many are benign, and a small proportion are serious. The important thing is not to decide which category applies before being assessed. A structured investigation does that quickly and safely.

What is haematuria?

Haematuria simply means red blood cells are present in the urine. It appears in two forms. Visible haematuria (also called macroscopic or gross haematuria) is seen with the naked eye — the urine appears pink, red, brown, or tea-coloured, and small clots may be present. Microscopic haematuria is invisible to the eye and is only detected on laboratory testing, either from a dipstick test confirmed by microscopy, or incidentally on a urine sample taken for another reason.

Both types warrant investigation. Visible haematuria carries a higher probability of a significant underlying cause and is treated with greater urgency. Persistent microscopic haematuria — particularly in a patient over 40 — is not trivial and should be investigated through a formal haematuria assessment pathway.

When to act immediately

For visible haematuria without these features, urgent outpatient referral within two weeks is appropriate under NICE NG12 guidelines for anyone aged 45 or over, or for any age with risk factors such as smoking history, previous pelvic radiotherapy, or occupational chemical exposure.

Common causes

The majority of patients investigated for haematuria will have a benign explanation, but the investigation exists specifically to exclude the causes that cannot be assumed away. Common causes include:

• Urinary tract infection — the most common cause of visible haematuria in younger women. Usually accompanied by stinging, frequency, and urgency. Should be treated and then the haematuria reassessed after a clear urine culture.
• Kidney or ureteric stones — classically accompanied by severe loin-to-groin colicky pain, though small stones can pass with minimal discomfort.
• Benign prostate enlargement — an enlarged prostate can bleed intermittently, particularly in older men with BPH.
• Bladder cancer — the most important diagnosis to exclude. Characteristically causes painless visible haematuria. More common in smokers and those over 60.
• Kidney cancer — haematuria is a presenting feature in roughly 30–40% of kidney cancer diagnoses. Often painless.
• Kidney disease — glomerulonephritis and other nephropathies typically cause microscopic haematuria alongside protein in the urine.

Blood thinners such as warfarin or apixaban can make bleeding more visible, but should never be assumed to be the sole cause. Anticoagulants reveal underlying pathology — they do not create it from nothing.

The investigation pathway

A structured haematuria assessment typically proceeds through four stages, all of which can be arranged through a specialist urology clinic without delay:

1. History and examination — the pattern of bleeding, associated symptoms, medications, risk factors, and a physical examination including a urine dipstick.
2. Laboratory tests — urine microscopy to confirm red blood cells, urine culture to exclude infection, blood tests to assess kidney function and rule out a bleeding disorder.
3. Imaging — CT urogram is the standard investigation for visible haematuria, providing detailed images of the kidneys, ureters, and bladder. Ultrasound is an alternative for younger patients or when radiation exposure is a concern.
4. Flexible cystoscopy — a brief outpatient procedure using a thin flexible camera passed through the urethra to examine the bladder directly. It takes approximately 10 minutes under local anaesthetic and is the only reliable way to exclude bladder pathology.

What happens if everything is normal?

A reassuringly normal investigation — negative cystoscopy and normal imaging — is the most common outcome. For a patient with a single episode of visible haematuria and no risk factors who is thoroughly investigated and found to be clear, routine GP monitoring is usually appropriate. Any recurrence should prompt re-referral.

For microscopic haematuria with a normal full investigation, ongoing monitoring of blood pressure and kidney function (to detect underlying renal disease) is recommended, with repeat urine tests at intervals. The question is not just urological malignancy — persistent microscopic haematuria can occasionally be the first sign of a kidney condition requiring nephrology input.

Questions to ask at your appointment

• Is my blood in urine visible, microscopic, or both — and does that change the urgency?
• Do I have any risk factors (age, smoking, previous radiotherapy) that make investigation more urgent?
• What does the investigation involve, and how quickly can it be arranged?
• If everything is normal, what follow-up do I need and for how long?